LOS ANGELES – Kelsey Grammer's return to "Frasier" is a cause for celebration, even if it requires reacclimating to Dr. Crane's tongue-twisting jokes, a hallmark of the original beloved NBC series.

Like the one involving Qinghai yak wool mattresses.

Filming the revival's second episode in front of an audience of hardcore fans at Paramount Studios last February, Grammer, 68, required mulligans for the complicated quip about the exotic handcrafted mattress Frasier had prepared for his grown son Freddy (Jack Cutmore-Scott).

Grammer, battling through a head cold, just kept rolling until he nailed the quintessentially snobby line that brought an appreciative audience to laughter. It signaled that "Frasier" is back, nearly two decades after signing off on NBC in 2004 after 11 Emmy-filled seasons.

"Even with a cold, with a few more takes than usual, there's no one who can navigate a line like that better than Kelsey Grammer," says Joe Cristalli, who created the new "Frasier" with Chris Harris. "That's his superpower."

Here's what you need to know about Grammer's "Frasier" return as the series streams weekly on Paramount+ starting Thursday (first two episodes will air on CBS on Oct. 17 at 9:15 EDT/PDT).

'Frasier' trailerShows Kelsey Grammer's return as Fraser Crane with a new Boston bar

'Cheers' creator James Burrows would have been 'blind' not to see greatness with 'Frasier'

Original "Frasier" director (32 episodes) and "Cheers" co-creator James Burrows was brought in to "sprinkle my pixie dust," he says, by directing the returning series' two leadoff episodes. Dr. Crane first appeared as the preppy, obnoxious boyfriend to Diane Chambers (Shelley Long) in the Season 3 "Cheers" premiere in September 1984, turning a bit part into an indelible nine-season role.

"We knew from the first five lines that this guy was amazing because he could compete with the stellar 'Cheers' cast," says Burrows. "Frasier was only written for a short character arc. But after the first show, we said, 'My God, we've got to keep this guy on.' We would have been blind not to see it."

Frasier eventually married Lilith Sternin (Bebe Neuwirth) and had a son Freddy. Lillith took care of Freddy in Boston as Frasier continued to evolve and move – to Seattle for his "Frasier" call-in radio show, to Chicago for that finale and now to Boston, where he takes a teaching job at Harvard for the revival.

"He's still that guy from the 'Frasier' show who commands respect, yet gives the highfalutin lines that make you want to kill him," says Burrows. "But Kelsey plays him with such vulnerability that you love Frasier."

Grammer retains the comedy gifts and still "looks the same" as when we last saw him in Seattle, says Burrows. "He just fits right into that role."

David Hyde Pierce did the 'hard thing' saying no to 'Frasier,' prompting a 'fresh' cast

John Mahoney, who played fusty Frasier's unpretentious father Martin in the original series, died in 2018 at 77. But the rest of the Seattle-set "Frasier" cast, including younger brother Niles (David Hyde Pierce), his wife Daphne (Jane Leeves) and radio producer Roz (Peri Gilpin), were originally supposed to return for the new series along with new cast members. That changed when Pierce declined the entreaties to bring back Niles.

"We had many conversations, but at some point, David said he didn't want to step into Niles' shoes again," says Cristalli. "It's a hard thing when everybody wants you to do it; Kelsey really wanted him to do it. But (Pierce) just didn't feel like he had anything left to offer his Niles character."

So Paramount called for an entirely new cast to surround Frasier in Boston. "They were already feeling the absence of John Mahoney, who's irreplaceable," says Cristalli. "So (they decided), let's not keep reminding people about the previous show. They strongly suggested a fresh start with an all-new cast."

Roz will appear in a late Season 1 episode, as will Lillith. "And hopefully, Daphne and Niles will show up in later seasons," says Cristalli.

How John Mahoney will forever appear on 'Frasier' in Freddy and the new bar

There are many tributes to the late Mahoney on "Frasier," including the new Boston bar setting: Mahoney's Taproom, with a sign that boasts "since 1940" (Mahoney's birth year).

"We named the bar Mahoney's in his honor," says Harris, who adds that Grammer immediately loved the idea. "This is someone who could never be replaced."

Obviously, it's a different saloon than "Cheers," the famed crosstown drinking hole Frasier alludes to in Episode 1, by discussing hanging out "too much in a certain bar" in his Boston past.

"You don't even have to say the name of the bar, but the audience knows exactly what you're talking about," says Burrows. "I begged the writers not to cut that line."

Mahoney's retired police officer Martin, the antithesis to Frasier's snobby ways, also endures in the grown Freddy, who dropped out of Harvard to become a firefighter and butts heads with his father.

"Freddy is like a walking tribute to John Mahoney," says Cristalli. "But Freddy brings a different color to what he can jab Frasier with. Freddy speaks French, knows wine regions and goes toe-to-toe in different ways."

Niles' son David appears on 'Frasier,' who else?

Niles and Daphne's grown son David (Ander Keith) did not fall far from his father's neurotic tree. "The audience will recognize Niles in David immediately," says Burrows.

Nicholas Lyndhurst stars as Frasier’s fellow Harvard professor Alan, Toks Olagundoye plays Harvard's psychology department head Olivia and Jess Salgueiro is Freddy’s roommate Eve.

With the new take, Cristalli is hopeful, but ever fretful of tarnishing the original's powerful legacy. "I live with the very real fear of killing the thing I love the most in the world," says Cristalli. "'Frasier' set such a high bar. But we're not trying to replicate that series. We had to evolve to a new place where it hopefully lives as a legacy."